This invention relates generally to conveyor sortation systems, or sorters, and, in particular, diverters used in such sortation systems. The invention is especially useful with sortation systems that, at least initially, divert articles without imparting a rotational motion on the article, also known as a parallel sorter. However, the invention is capable of other applications.
Various forms of conveyor sortation systems have been known, such as paddle diverters, pushers, pop-up chain and belt transfer assemblies, and the like. One particular advantageous form of a sortation system is a positive displacement sortation system in which a series of pusher shoes are mounted to travel in the direction of the conveying surface and, when diverted, to travel laterally along the conveying system to divert articles on the conveying surface. For example, articles may be diverted to takeaway conveyors, or spurs, arranged either on one side of the conveying surface, thereby defining a unilateral divert, or on both sides of the conveying surface, thereby defining a bilateral divert. The pusher shoes are propelled laterally by a propelling assembly extending below the conveying surface and selectively engaging a diverter rail which extends diagonally under the conveying surface. Diverters associated with the diverting rail selectively divert the propelling assemblies onto the associated diverting rail in order to cause the pusher shoes to travel laterally of the conveying surface. If a particular pusher shoe is not diverted onto a particular diverting rail, then the shoe continues to travel solely in the direction of the conveying surface unless a downstream diverter diverts the pusher shoe onto its associated diverter rail. Examples of such positive displacement sorters are disclosed in commonly assigned U.S. Pat. Nos. 4,738,347 and 5,127,510, the disclosures of which are hereby incorporated herein by reference. Other examples of positive displacement sorters are disclosed in U.S. Pat. Nos. 3,361,247 and 4,884,677.
One form of a diverter is disclosed in U.S. Pat. 5,409,095, the disclosure of which is hereby incorporated herein by reference. The ""095 patent discloses a diverter made up of an electromagnet that, when energized, attracts the propelling assembly of the pusher shoe and guides the propelling assembly onto the associated diverting rail. In the embodiment illustrated in the ""095 patent, the propelling assembly includes a bearing made of a ferromagnetic, or magnetically permeable, substance, such as iron alloy. The electromagnet, when energized, attracts the bearing thereby diverting the associated pusher shoe onto the diverting rail associated with the diverter. The electromagnetic diverter disclosed in the ""095 patent is desirable because it is capable of diverting pusher shoes traveling at a high rate of speed thereby increasing the throughput of articles sorted by the sorter. Additionally, the pusher shoes can be diverted with less noise than is produced with mechanical or electromechanical diverters.
A particularly advantageous form of a sorter is one which, at least initially, diverts articles without rotating the articles. Such a parallel divert sorter is disclosed in commonly assigned U.S. Pat. Nos. 5,165,515; 5,927,465 and 6,041,909 and pending U.S. patent application Ser. No. 09/606,610 filed Jun. 29, 2000, by J. Shearer, Jr. et al. entitled CONVEYOR SYSTEM WITH DIVERTING TRACK NETWORK, the disclosures of which are hereby incorporated herein by reference. Because the articles are at least initially diverted without rotating the articles, it is possible to include a smaller gap between articles because it is not necessary to leave sufficient gap for rotation of the articles. This also improves the throughput of the sorter. One difficulty of using an electromagnetic diverter with a parallel divert sorter is that it may be necessary to space the diverting rails and diverters as close together as the pitch between the pusher shoes. Because pusher shoe pitch may be as low as 5 or 6 inches, it may be necessary to utilize as low as 5-inch or 6-inch spacing between magnetic diverters. Because of the electromagnetic force necessary to attract the bearing of a pusher shoe in order to divert that pusher shoe onto a diverting rail, the size of the electromagnetic diverter becomes prohibitive for use in a parallel divert sorter of the type disclosed in the ""515, ""465, and ""909 patents and the U.S. Pat. No. 09/606,610 pending application.
According to one aspect of the invention, a positive displacement parallel sorter includes a conveying surface, a plurality of pusher shoes capable of traveling laterally of the conveying surface to divert articles on the conveying surface, a plurality of diverting rails extending diagonally under the conveying surface and a plurality of diverters made up of electromagnetic actuators associated with the diverting rails. Corresponding portions of the pusher shoes are separated from each other in the direction of travel of the conveying surface by a shoe pitch. The actuators are substantially separated from each other by no more than the shoe pitch. The pusher shoes include a transfer assembly below the conveying surface having a pilot member made of a magnetically permeable material. A pusher shoe is selectively diverted to one of the diverting rails by the actuator associated with that diverting rail magnetically attracting the pilot member associated with that pusher shoe to magnetically initiate a divert. The transfer assembly associated with the pusher shoe mechanically completes the divert that is magnetically initiated. Because the magnetic assembly is diverting the pilot and not the entire shoe, the required diverting force is significantly less. Therefore, the size of the electromagnetic diverter may be substantially reduced to accommodate close spacing.
According to another aspect of the invention, a positive displacement parallel sorter includes a conveying surface, a plurality of pusher shoes capable of travelling laterally of the conveying surface to divert articles on the conveying surface, a plurality of diverting rails extending diagonally under the conveying surface and a plurality of electromagnetic actuators associated with the diverting rails. The pusher shoes include a transfer assembly below the conveying surface. The transfer assembly includes a pilot member made up of a magnetically permeable material, an intermediate low-friction member and a trailing low-friction member. The low-friction members are made up of a non-magnetically permeable material. The pilot member, intermediate member, and trailing member are commonly mounted on a toggle member that is pivotally mounted with respect to the article-contacting member of the pusher shoe. A divert is initiated by one of the actuators attracting the pilot member. This provides a diverting arrangement which diverts within a minimum amount of force and in a minimum amount of space.
According to another aspect of the invention, a sorter includes a conveying surface, a plurality of pusher shoes capable of travelling laterally of the conveying surface, the pusher shoes having article-contacting members extending at least partially above the conveying surface to divert articles on the conveying surface. A plurality of diverting rails extend diagonally under the conveying surface and a plurality of diverters are associated with the diverting rails. The pusher shoes include a transfer assembly below the conveying surface. Each of the diverters includes an actuator for selectively diverting the laterally propelling assembly toward the associated one of the diverting rails to initiate a divert and a stationary curved surface for guiding the transfer assembly towards the associated one of the diverting rails. This arrangement substantially reduces noise resulting from the required change in direction of the lateral propelling assembly as it is diverted towards the associated diverting rail. Preferably, the tangent of a portion of the curved surface is aligned with the associated ones of the diverting rails in order to direct the transfer assembly toward the associated one of the diverting rails.
According to another aspect of the invention, a sorter includes a conveying surface, a plurality of pusher shoes capable of travelling laterally of the conveying surface, the pusher shoes having article-contacting members extending at least partially above the conveying surface to divert articles on the conveying surface. A plurality of diverting rails extend diagonally under the conveying surface and a plurality of diverters are associated with the diverting rails. The pusher shoes include a transfer assembly below the conveying surface. The diverters include an actuator for selectively actuating the transfer assembly toward the associated one of the diverting rails to initiate a divert. The diverters include a guide rail. The lateral propelling assembly passes between the actuator and the guide rail when not being diverted. A magnet and magnetically permeable material are provided, respectively, on the transfer assembly and the guide rail, or vice versa, to maintain contact between the transfer assembly and the guide rail when the lateral propelling assembly is not being diverted. This reduces the possibility of a false divert.
According to another aspect of the invention, a sorter includes a conveying surface, a plurality of pusher shoes capable of travelling laterally of the conveying surface, the pusher shoes having article-contacting members extending at least partially above the conveying surface to divert articles on the conveying surface. A plurality of diverting rails extend diagonally under the conveying surface and a plurality of diverters are associated with the diverting rails. The pusher shoes include a transfer assembly below the conveying surface for transferring that pusher shoe when engaging one of the diverter rails. Each of the diverters includes an actuator for selectively actuating the transfer assembly toward the associated one of the diverting rails. The sorter further includes means for ensuring that an initiated divert of the transfer assembly will be completed.